Added a list of Syntax Highlighting languages

I stumbled on the list through a Github Flavored Markdown guide from @adam-p here:
https://github.com/adam-p/markdown-here/wiki/Markdown-Cheatsheet#wiki-code

Which linked through to here:
http://softwaremaniacs.org/media/soft/highlight/test.html

After that, I copied the languages and their identifiers into a table so it's easy for users to see which languages they can use for syntax highlighting.

I was thinking of providing a separate page with the table since it's a rather long list. If you want that I'll make a new commit and update the pull request.

Let me know what you think :)

Dries